a) Dancerous, adj., When dance spreads rapidly and becomes contagious and uncontrollable inducing smiling and happiness. Much like a laughing fit but with much more flailing.

b)Dancerous, adj., Of or relating to a viral ailment of the torso, arms, and legs which causes the afflicted to uncontrollably twitch and move in rhythmic, seemingly coordinated patterns

I'm sorry ma'am, but the affliction seems to be dancerous. Prognosis: Terminal grooviness.

Man, I'm goin' to the club! Ya know, that 'effin dancerous one!?

Sun, alcohol, friends, and dank beats have all been linked to dancerous situations but research is still needed to conclude an absolute cause. To date the only cure known is to literally dance your ass off.